Of all things - a straight rasor. I bought it through "The Duluth Trading Company," and it is useless as a rasor. Too thick a blade, not a fine enough steel. But it's durable, with a handsome wood handle, and lends a touch of panache. But if I did your heavy-duty work, I'd carry my classic folding Buck.
Opinel makes great knives. Many of them are between 10-20 bucks and they're great. I continuously buy them because the quality vs price is a super great deal.
Kershaw Blur is a little pricey but it's been worth every penny so far.
Caveat - I collect pocketknives (mostly traditional patterns) - and am willing to spend money on good blades (and what I decide is good varies widely).
My current favorite modern folder for EDC use is the Spyderco Southard. I had mine modified with carbon fiber scales (grip better when damp, and don't tear up jeans the way G10 can), and a deep carry custom clip. The ergonomics of the knife are amazing, and the CTS-204P blade steel holds a tremendous edge.
I usually pair that with a traditional folder in 1095 carbon steel, typically a barlow or other two bladed jack. My current favorite new production knives come from Great Eastern Cutlery (Northfield, Tidoute, and Northwoods knives). Impeccable workmanship, and great materials.
On my keys is always a micro leatherman - I don't use the blade on it, but the scissors and other tools are handy.
Swiss Army - Recruit
Not gonna stop a mugging, but it holds an edge and isn't a burden to carry around.
Gerber Paraframe. Not great, but good enough.
I work in an office so it is good enough for the basic day to day usage. And I tend to misplace my knives (or they walk off - possibly with help), so at less than $20 I don't feel bad when I inevitably can't find it and have to get a new one.
But I also have 2 or 3 other knives and a Leatherman Wave in the backpack I pretty much always carry.
Bit o'Trivia about Leatherman; I interviewed an executive for a business article. To quote myself:
The company’s rugged name is not clever marketing; Leatherman Tool Group was co-founded in 1983 by Tim Leatherman. After graduating from Oregon State University with a degree in mechanical engineering, he traveled through Europe in what he calls an untrustworthy $300 Fiat. He used his Boy Scout knife often for minor repairs but remarked, “I kept wishing I had a pair of pliers!” and designed a multi-tool with just the capabilities he needed.
When I was a kid in England, every gentleman carried his "pen knife," as they were known. Parcels came with string, not tape; grinding pencil sharpeners were not the norm. Older boys in my school (beginning age 12 were issued a pen knife. Anyone who'd been a boy scout, or in the military, had developed the habit.
Perhaps there's an anti-gender-normative/nonsensically progressive thing going on here; I can't think of many dads where I live (in Massachusetts) who'd give their sons an "edged weapon," as they're likely seen.
Hell, there is even an "electricians" knife. Specifically. I have several in my collection.
The biggest problem I see is zero tolerance policies in schools. Even a SAK classic (with a non locking 1.25" blade) carried by a japanese girl for cleaning rosin from her violin strings, has resulted in summary expulsion from school. Taking away the ability for schools (and teachers/administrators) to use their own judgement.
I will be giving my boy a pocket knife once I'm sure he can be safe with it - but I'll worry that he'll forget and accidentally take it to school.